Fuel feed devices for internal engines

ABSTRACT

In the intake pipe upstream of the main throttle is an auxiliary throttle which opens automatically and proportionately to the air flow. Liquid fuel is injected downstream of the main throttle. A metering system sensitive to the auxiliary throttle at least for certain operational conditions keeps the air/fuel mixture constant, the fuel injection is controlled by an electromagnetic valve. The metering system consists of a rotating member controlling the current to the electromagnet so as to open the injector over only a fraction of each turn, this fraction varying directly as the opening of the auxiliary throttle. A pressure regulator on the delivery pipe of the fuel pump has a discharge valve which opens under the effect of the delivery pressure and closes under the effect of suction in the intake pipe between the two throttles. The discharge valve is coupled to a diaphragm to which the suction is transmitted by a linking channel, which has a choke to ensure smaller flow from the intake pipe to the diaphragm than in the reverse direction.

United States Patent Arnaud 1 Sept. 5, 1972 [72] Inventor: GastonArnaud, Paris, France [73] Assignee: Societe Industrielle de Brevets etdEtudes S.I.B.E., Seine, France [22] Filed: April 12, 1971 [21] Appl.No.: 133,009

[30] I Foreign Application Priority Data April 30, 1970 France ..70l6102[52] US. Cl. ..123/l39 AW, 123/119 R, 261/50 A [51] Int. Cl ..F02m 51/02[58] Field of Search...123/l 19 R, 139 AW; 261/50 A Neuilly-sur PrimaryExaminer-Wendell E. Burns AttorneyStevens, Davis, Miller & MosherABSTRACT In the intake pipe upstream of the main throttle is anauxiliary throttle which opens automatically and proportionately to theair flow. Liquid fuel is injected downstream of the main throttle. Ametering system sensitive to the auxiliary throttle at least for certainoperational conditions keeps the air/fuel mixture constant, the fuelinjection is controlled by an electromagnetic valve. The metering systemconsists of a rotating member controlling the current to theelectromagnet so as to open the injector over only a fraction of eachturn, this fraction varying directly as the opening of the auxiliarythrottle. A pressure regulator on the delivery pipe of the fuel pump hasa discharge valve which opens under the efl'ect of the delivery pressureand closes under the effect of suction in the intake pipe between thetwo throttles. The discharge valve is coupled to a diaphragm to whichthe suction is transmitted by a linking channel, which has a choke toensure smaller flow from the intake pipe to the diaphragm than in thereverse direction.

2Claims,2DrawingFigul-es PATENTEDSEP 5 I972 SHEET 1 OF 2 lamo FUEL FEEDDEVICES FOR INTERNAL ENGINES The invention relates to fuel feed devices,for internal combustion engines, of the type of those which comprise, onone hand, in their intake pipe, upstream of a principal throttle memberactuated by the driver, an auxiliary throttle member which opensautomatically and progressively in proportion as the flow of air in thesaid pipe increases, on the other hand, means for injecting underpressure liquid fuel into that portion of this pipe situated downstreamof the main throttle member and, on the other hand lastly, a meteringsystem sensitive to the position of the auxiliary throttle member andadapted to regulate the flow of injected fuel in such a way that therichness of the air/fuel mixture passing into the intake pipe issubstantially constant, at least for certain conditions of operation ofthe engine, the abovesaid injection means being constituted by a sourceof fuel under pressure of which the delivery circuit opening into theabove-said portion of the intake pipe is controlled by at least onevalve actuated by an electromagnet.

The invention relates more particularly to those devices of the typeconcerned which have been described in US. Pat. No. 3,543,739 of Oct. 9,1968 to Andre Louis Mennesson and of which the abovesaid metering systemcomprises a member driven in continuous rotation and capable, by actingon the energization of the electromagnet, of determining over a fractiononly of each of its revolutions the opening of the valve, this systembeing arranged so that it increases or decreases the said fraction inproportion as the opening of the auxiliary throttle member increases ordecreases respectively.

The invention relates more particularly again to those devices of thetype concerned of which the source of fuel under pressure is constitutedby a fuel pump on the delivery pipe of which acts a pressure regulatorwhich comprises a discharge valve tending to open under the effect ofthe delivery pressure of the pump and to close under the effect of thesuction existin g in the zone of the intake pipe comprised between itstwo throttle members, which suction is transmitted through a linkingchannel on to a diaphragm to which the discharge valve is coupled.

Of course the position of the auxiliary throttle member ischaracteristic of the flow of air passing from upstream to downstream ofthis member. If the volume of the portion of the intake pipe comprisedbetween the intake valves of the internal combustion engine and the mainthrottle member is considerable with respect to the stroke volume of theengine, the flow of air measured by the auxiliary throttle member is notstrictly equal, at transient speeds (acceleration or deceleration), tothat which is in fact absorbed by the engine at the same moment. t

For example, on brisk deceleration, the flow of air measured by theauxiliary throttle member drops rapidly through the closing of the mainthrottle me e n e r and. until heestah ishrnentg poor, the operation ofthe engine then no longer being satisfactory.

In order to overcome this drawback, the feed device of the type definedabove is characterized by the fact that on the abovesaid linking channelare arranged throttle means ensuring a smaller flow cross-section in thesense going from the abovesaid zone of the intake pipe to the diaphragmof the pressure regulator than in the reverse direction.

Due to this construction, the speeds of variations of the suctiontransmitted to this diaphragm are adjusted in such a way that, even onaccelerations and decelerations, the richness of the air/fuel mixture ismaintained substantially constant.

In order that the invention may be more fully understood, a preferredembodiment of a carburetter ac cording to the invention is describedbelow purely by way of illustrative and non-limiting example, withreference to the accompanying drawings in which:

FIG. 1 shows in diagrammatic elevation with portions in cross-sectionone embodiment of a fuel feed device constructed according to theinvention; and

FIG. 2 shows a section of the embodiment of FIG. 1 along the line 11-11.

According to the invention, and more particularly according to that ofits methods of application, as well as according to those of its methodsof production of its various parts, to which it would appear thatpreference should be given, in order to construct a fuel feed device forvehicle engines or the like, procedure is as follows.

As regards the device as a whole, it is constituted in any suitablemanner such that it comprises:

on one hand, in its intake pipe 1, upstream of a main throttle member 2actuated by the driver, an auxiliary throttle member 3 which opensautomatically and progressively in proportion as the flow of air in thepipe 1 increases, the direction of flow being indicated by the arrow Fin FIG. 1;

on the other hand, means for injecting liquid fuel under pressure intothe portion of the pipe 1 situated downstream of the main throttlemember 2; i on the other hand lastly, a metering system sensitive to theposition of the auxiliary throttle member 3 and adapted to regulate theflow of fuel injected in such a way that the richness of the air/fuelmixture passing into the pipe 1 is substantially constant, at least forcertain conditions of operation of the engine.

In the embodiment shown, the auxiliary throttle member 3 is constitutedby a butterfly valve keyed on an axle 4. This valve is actuated by apneumatic device comprising a diaphragm 5 separating two chambers 6 and7 from one another. The chamber 6 is connected by a channel 8 to achamber 9 constituted by the zone of the pipe 1 which is comprisedbetween the main throttle member 2 and the valve 3. The axle 4 isrigidly fixed to a lever 10, provided at its free end, with a pin 11which cooperates with the end of a rod 12, which is connected to thediaphragm 5. A spring 13 tends constantly to close the valve 3 againstthe action of the suction transmitted into the chamber 6. The chamber 7is placed at atmospheric pressure through a channel 14 startingpreferably from the air intake 15 of the pipe 1.

Of course the angular position taken up at any moment inside the pipe 1by the valve 3 corresponds to the flow of air which flow in this pipe.The greater the delivery of air, the more the valve 3 opens, asubstantially constant suction (or varying according to thecharacteristics of the spring 13) being established in the chamber 9comprised between the two throttle members 2 and 3. The valve 3 could bereplaced by equivalent throttle members, of which examples have beendescribed in the above-said patent.

The abovesaid injection means are constituted by a source of fuel underpressure which will be described in more detail below and of which thedelivery circuit opening into the pipe 1 downstream of the main throttlemember 2 is controlled by at least one valve 16 actuated by anelectromagnet 17.

g The metering system is made to include a flat and opaque disc 18 whichis borne by a shaft 19, connected preferably to the internal combustionengine (not shown) supplied by the device, so that the disc is driven incontinuous rotation around an axis perpendicular to its plane. The disc18 is interposed between a radiation or light source 20 and a radiationreceiver such as a photodiode or photoelectric cell 21, home by a commonsupport 22 connected to the auxiliary throttle member 3 and it ispierced by at least one window 23 adapted to allow the radiation beamemerging from the source 20 to arrive at the cell 21. The cell 21 isarranged to actuate the energization of the electromagnet 17 accordingas it is irradiated or not and the assembly is such that theelectromagnet is energized over a fraction of each of the revolutions ofthe disc 18 which varies in the same sense as the degree of opening ofthe throttle member 3.

The radiation source 20 can be constituted by a lamp which is adapted tobe supplied by a battery 24 as soon as the ignition contact 25 of theengine is closed and which is arranged in a hollow boss 26 pierced by ahole. This hole is oriented in such a way as to direct a light beam onto the cell 21, through a hole passing through a hollow boss 27 wherethe said cell is housed.

In the embodiment shown, the bosses 26 and 27 are carried by the ends ofthe U-support 22 which straddles the disc 18 so that the source 20 andthe cell 21 are on opposite iatfi'r'ih disc and which is rigidly fixedto the axle 4, the latter being parallel to the shaft 19 as well as tothe light beam received by the cell 21.

To utilize the currents generated in the cell 21, there may be insertedbetween the latter and the electromagnet 17, an amplifying relay 28.

When the internal combustion engine possesses several cylinders eachsupplied by a valve 16 actuated by an individual electromagnet 17, allthe electromagnets can be actuated simultaneously or by means of adistributor 30 synchronized with the disc 18 in order to sendsuccessively the intermittent energizing current into the differentelectrom agnets, the disc possessing as many windows 23 as cylinders tobe supplied. These windows are distributed regularly around the shaft 19and each have a shape such that a fraction of a turn of disc 18 duringwhich it enables the cell 21 to be irradiated normally increases inproportion as the throttle member 3 opens, that is (in the embodimentshown) in proportion as the bosses 26, 27 approach the shaft It is knownthat the supply device which has just been described has the followingoperation.

In proportion as the flow of air in the pipe 1 increases, the throttlemember 3 opens thereby driving the support 22 in the direction whichbrings the bosses 26 and 27 closer to the shaft 19. Each of thepositions of the bosses corresponds to adifferent radius of the disc 18.

Since the shape of each window 23 has been determined so that thefraction of a turn during which it allows the light ray from the source20 to pass towards the cell 21 (creation of a current in the conductor31) increases in proportion as the latter elements 20, 21 approach theshaft 19, it is ensured that the flow of fuel delivered by eachinjection valve 16 varies in the same sense as the flow of air in thepipe 1.

Having arranged this, the source of fuel under pressure is constitutedby a fuel pump of which the suction pipe 51 dips into a fuel reservoir52 and on the delivery pipe 53 of which acts a pressure regulator 54.The latter comprises a discharge valve 55 tending to open under theeffect of the delivery pressure of the pump and to close under theeffect of the suction existing in the chamber 9, which suction istransmitted through a linking channel 56 onto a diaphragm 57 to whichthe val ve 55 is coupledby a rod 58. The valve 55 cooperates with a seat59 which constitutes the outlet from a chamber 60 connected through aby-pass linking channel 61 to the delivery pipe 53. The linking channel56 ends at a variable volume chamber 62 limited by one face of thediaphragm, the other face being placed at atmospheric pressure, forexample through an orifice 63. The assembly is such that the valve 55opens as soon as the pressure in the pipe 53 exceeds a value determinedby the surface of the diaphragm 57 and by the suction exerted on thelatter.

Assuming that the intake pipe 1 comprises, downstream of the mainthrottle member 2, a volume 64 large with respect to the stroke volumeof the engine, according to the invention, there is arranged on thelinking channel 56 throttle means 65 ensuring a flow section s maller inthe direction a (FIG. 1) going from the chamber 9 to the chamber 62limited by the diaphragm 57 than in reverse direction (direction b).

Advantageously, the throttle means 65 are constituted by two calibratedorifices 66a and 66b, mounted respectively in the two parallel branches56a and 56b of the linking channel 56, and by a nonretfinvalve 67uiiedbya spring 68, which valve is arranged in series with one (66b) of thecalibrated orifices and arranged to allow air to pass in the secondabove-indicated direction (direction b).

The operation of the supplementary means according to the presentimprovements is as follows.

In the case of deceleration, i.e. on closing of the main throttle member2, the flow of air entering the volume 64 is smaller than that which isadmitted to the engine, since the pressure in this volume 64 diminishes.Since the position of the auxiliary throttle member 3 measures the flowof air passing through it, and not that which is absorbed by the engine,there is as a result an air/fuel mixture which is too poor in fuel.However, according to the said improvements, the speed of drop in fuelpressure, on deceleration, is limited by the presence of the orifice66a. In fact, to lower the fuel pressure, air must flow in the directionof the arrow a. Since the spring 68 supports the valve 67 on its seat,air can only pass through the orifice 66a. The speed of drop in fuelpressure is all the less as the orifice 66a is smaller.

On acceleration, in similar manner, the speed of increase in fuelpressure is limited. In this case, air flows ni h q j t q mq the rsliban the, irre ssss through the two orifices 66a and 66b.

A judicious choice of these two orifices thus enables an almost constantrichness of air/fuel mixture to be maintained, even during transientconditions (acceleration and deceleration) of the internal combustionengine.

As is self-evident and as emerges already from the precedingdescription, the invention is in no way limited to those of its methodsof application, nor to those of its methods of production of its variousparts, which have been more especially indicated; it encompasses, on thecontrary, all variations.

I Claim:

1. Fuel feed device, for an internal combustion engine, which comprises,in its intake pipe upstream of a main throttle member actuated by thedriver, an auxiliary throttle member which opens automatically andprogressively in proportion as the flow of air in the said pipeincreases, means for injecting liquid fuel under pressure into thatportion of said pipe situated downstream of the main throttle member,and a metering system sensitive to the position of the auxiliarythrottle member and adapted to regulate the flow of fuel injected insuch a way that the richness of the air/fuel mixture passing into theintake pipe is substantially constant, at least for certain operationalconditions of the engine, said injection means being constituted by asource of fuel under pressure of which the delivery circuit opening intosaid portion of the intake pipe is controlled by at least one valveactuated by an electromagnet, the metering system comprising a memberdriven in continuous rotary movement and capable, by acting on theenergization of the electromagnet, of determining over a fraction onlyof each of its turns the opening of the valve, said system beingarranged so that it increases and decreases said fraction in proportionas the opening of the auxiliary throttle member increases and decreasesrespectively, said source of fuel under pressure being constituted by afuel pump on the delivery pipe of which pump a pressure regulator acts,said regulator comprising a discharge valve tending to open under theeffect of the delivery pressure of the pump and to close under theeffect of the suction existing in the section of the intake pipecomprised between its two throttle members, a linking channeltransmitting said suction on to a diaphragm to which the discharge valveis coupled, throttle means being arranged on said linking pipe to ensurea smaller flow cross-section in the direction going from said section ofthe intake pipe to the diaphragm of the pressure regulator than in thereverse direction.

2. Fuel feed device according to claim 1, wherein the throttle means areconstituted by two calibrated orifices, mounted respectively in twoparallel branches of the linking pipe, and by a non-return valvearranged in series with one of the calibrated orifices and arranged toallow air to pass in said reverse direction.

1. Fuel feed device, for an internal combustion engine, which comprises,in its intake pipe upstream of a maiN throttle member actuated by thedriver, an auxiliary throttle member which opens automatically andprogressively in proportion as the flow of air in the said pipeincreases, means for injecting liquid fuel under pressure into thatportion of said pipe situated downstream of the main throttle member,and a metering system sensitive to the position of the auxiliarythrottle member and adapted to regulate the flow of fuel injected insuch a way that the richness of the air/fuel mixture passing into theintake pipe is substantially constant, at least for certain operationalconditions of the engine, said injection means being constituted by asource of fuel under pressure of which the delivery circuit opening intosaid portion of the intake pipe is controlled by at least one valveactuated by an electromagnet, the metering system comprising a memberdriven in continuous rotary movement and capable, by acting on theenergization of the electromagnet, of determining over a fraction onlyof each of its turns the opening of the valve, said system beingarranged so that it increases and decreases said fraction in proportionas the opening of the auxiliary throttle member increases and decreasesrespectively, said source of fuel under pressure being constituted by afuel pump on the delivery pipe of which pump a pressure regulator acts,said regulator comprising a discharge valve tending to open under theeffect of the delivery pressure of the pump and to close under theeffect of the suction existing in the section of the intake pipecomprised between its two throttle members, a linking channeltransmitting said suction on to a diaphragm to which the discharge valveis coupled, throttle means being arranged on said linking pipe to ensurea smaller flow crosssection in the direction going from said section ofthe intake pipe to the diaphragm of the pressure regulator than in thereverse direction.
 2. Fuel feed device according to claim 1, wherein thethrottle means are constituted by two calibrated orifices, mountedrespectively in two parallel branches of the linking pipe, and by anon-return valve arranged in series with one of the calibrated orificesand arranged to allow air to pass in said reverse direction.